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September 15, 2008

700 Fish Populations at Risk Many Problems Caused By Humans Through Pollution, Development

by Sam Savage

By STEVE PATTERSON

From the St. Johns River to the Pacific Northwest, freshwater fish are in trouble, say scientists who report nearly 40 percent of fish species in North American rivers are declining substantially.

The 700 distinct fish populations that are imperiled are nearly twice what a similar investigation in 1989 discovered.

Much of the decline is in the Southeast. Florida is less affected than its neighbors but has 23 imperiled populations, from minnows to bass. About one-third are in the St. Johns or in waterways connecting to it.

All of the fish matter, a leader of the research said.

"The minnow is the food for the bass that is eventually consumed by the human. And if these waters aren't fit for the minnow, there's a point where you question how safe is it for us to recreate in," said Howard Jelks, a fish biologist for the U.S. Geological Survey in Gainesville.

Jelks is the lead writer on a study in the journal Fisheries, outlining research by about 150 scientists in Mexico, the U.S. and Canada.

People have caused many of the problems afflicting fish, the scientists reported, saying pollution and development hurt habitat while a global economy has helped spread non-native species that compete for food.

"Fish are aquatic organisms and it seems that all of our aquatic organisms are in similar trouble, if they're insects, crayfishes, mussels," Jelks said. "The interesting thing about aquatic systems is they accumulate all of the problems that we create."

All of those concerns have been heard before along the St. Johns, where silting and damage to underwater grass beds have affected some of the smallest fish. Outside species such as blue tilapia, an African fish introduced to the Southeast a few decades ago, add stress by competing for food and breeding grounds.

Fish "live in a freshwater habitat that's pretty much under assault by people," Duke University marine biologist Larry Crowder told The Associated Press. "Things are tanking all around us. When does it have to be bad enough to get people's attention?"

At least eight fish listed as imperiled were found historically in the St. Johns and connected waterways. Some, such as the snail bullhead catfish, have been considered vulnerable only in recent years. By contrast, the shortnose sturgeon has been virtually absent from the river since at least 1950.

The imperiled included small populations tied distinctly to one area, such as the Lake Eustis pupfish found in a few lakes that feed the Ocklawaha River, the largest tributary of the St. Johns.

Also on the researchers' trouble list were gulf sturgeon and spotted bullhead catfish, both found in the Suwannee River in rural North Florida, where sturgeon have become famous for leaping into painful collisions with boaters.

Striped bass, favorites for sportsmen, were considered imperiled on the Gulf coast but not along Florida's east coast.

Other parts of the Southeast fared worse. Georgia had 58 imperiled populations, and Alabama had 68.

That may be partly because those areas had more freshwater diversity to begin with, Jelks said.

He noted that researchers were counting not only species but subspecies and populations that were unique to one place.

Mexico fared worst of all, with nearly half of its populations in jeopardy. About one-third of populations in America are imperiled, including salmon in the Pacific Northwest, and only about a tenth of the fish in Canada.

Anthony Ricciardi, a McGill University biologist who was not part of the research, told the AP that freshwater extinctions have been happening at a faster pace, but remained almost unnoticed.